<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>三角形巧妙运用</title>
    <style>
        .triangle {
            width: 0;
            height: 0;
            border-top: 100px solid red;
            border-bottom: 100px solid green;
            border-right: 100px solid yellow;
            border-left: 100px solid blue;
        }
        .content {
            width: 200px;
            height: 200px;
            background-color: orange;
            position: relative;
        }
        .smallT {
            width: 0;
            height: 0;
            border: 20px solid transparent;
            border-left: 20px solid orange;
            position: absolute;
            right: -40px;
            top: 100px;
        }
    </style>
</head>
<body>
    <div class="triangle">
    </div>
    <div class="content">
        <div class="smallT"></div>
    </div>
</body>
</html>